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Re: brine shrimp enrichment questions

Sorry for not "getting with the program" on this brine shrimp enrichment
issue sooner.  Please feel free to share my comments.

Happy Halloween to all,
David Kawahigashi
baybrand at best_com

> >Do you put the emulsion in the hatching solution with the
> >cysts or after they hatch?

It is not recommended to add the enrichment emulsion directly to the
hatching water due to the high levels of bacteria that have proliferated
during incubation of the eggs.  Addition of the enrichment without high
levels of bacteria would drop the dissolved oxygen level significantly
and reduce hatching efficiency.  Adding the enrichment to a 'bacterial
soup' would be even worse.  Thus, you should harvest the hatched Artemia
as normal, rinse them through a fine mesh net, and put about 50% of the
hatched nauplii in the same vessel filled with new salt water before
adding the enrichment. You may need to add more 'enrichment vessels' if
you want to enrich the entire hatch.   
> >
> >How long after the BBS hatch do you harvest?
You may harvest the hatched nauplii anytime after 100% of the eggs have
hatched.  At optimum temperatures of 28-30C (or around 80F) most of the
eggs should have hatched after 18-20 hours.  Most hatcheries I know of
use a 24 hour hatching schedule.  The Instar II stage (when the nauplii
develops a mouth and a gut) usually occurs between hour 28 - 36 from
time of stocking.  The nauplii can be harvested as late as the Instar II
stage.  But to avoid increased bacteria and ammonia levels in the
hatching vessel, I would recommend harvesting the nauplii after 24
hours, transfering them to another clean vessel, and adding the emulsion
around 6 hours later.  

> 2)  How much of the stuff do I add?

According to manufacturers instructions, .3 grams per liter is more than
sufficient.  I believe that around 20 drops if emulsion equals one gram,
so 7-8 drops should be sufficient.  Instead of dropping the drops of
emulsion directly into the hatching vessel, I use a small vial or test
tube, half filled with water.  Simply add the emulsion, shake it up and
add it to the vessel.   

> 3)  When do I harvest the Artemia?
Instar II nauplii should be enriched for a minimum of 12 hours to fully
pack the gut and some of the tissues.  Most marine finfish hatcheries
enrich for 24 hours.  If mortalities occur during the enrichment
process, increase the aeration so that the water is "boiling".  This
will not injure the feeding nauplii.  Adding sodium bicarbonite, to
maintain a pH above 7.0, also helps improve water conditions (and

> 4)  How long are the enriched Artemia good for?
Once the Artemia have been harvested and introduced to the fish tank,
the filter-feeding behavior continues as the Artemia filter whatever
particles are in the tank and 'poop out' the enrichment formula from
their gut.  So the sooner the fish or invertebrates are able to consume
the enriched Artemia, the more HUFA's are delivered to your fish
(Artemia are just the delivery mechanism).  

To avoid the process of having to hatch and enrich before every feeding,
storage of the already enriched Artemia is highly recommended.  After
harvesting, rinsing, and feeding of the enriched Artemia, pour the
remainder into a shallow dish along with some clean salt water (no more
than 1/4" deep) and store in the refrigerator.  No aeration is
necessary.  At 4C, the metabolism is slowed way down and the ingested
enrichment will stay intact for at least another 24 hours for later

> 5) Can I use lipid emulsions to enrich other foods?  

Enrichment emulsions or fish oils have been used to 'coat' pelleted
feeds before feeding.  Some of the lipids would be absorbed into the
pellet, but most of it would form an 'oil slick' on the surface of your
tank.  Bioencapsulating live brine shrimp is a better alternative.  Live
rotifers and copopods can also be enriched.  
> 6)  What are the symptoms of essential fatty acid deficiency?
Lipids or phospholipids are the primary energy depots for marine fish
and invertebrates and serve as important links to hormonal functions,
reproduction, and growth.  Since long chain (omega-3) fatty acids cannot
be synthesized by the marine species, it must be incorporated into the
diet.  Deficiencies of the omega-3's (DHA and/or EPA) in the diet will
result in reduced natural defences and eventual death from infections,
diseases and other secondary effects.